This invention relates to electrocardiography (ECG) and more particularly to automatic sensing of ECG lead failure and automatic switching of the ECG lead configuration in response thereto.
In electrocardiography, a plurality of electrodes with attached leads (hereinafter leads) are applied to selected regions of a patient's body in order to sense electrical signals generated thereon in response to the patient's heart muscle activity. A number of standard lead configurations have come into common practice involving three, five and even twelve leads.
The opposite ends of the leads are coupled to an isolated ECG preprocessor including a lead switch where electrical signals are combined in a well known predetermined fashion depending on which lead configuration has been selected by the attending individual. The output signal resulting from this combination (after suitable filtering and amplification) is the patient's electrocardiogram or ECG signal.
In some known digital ECG monitors, the ECG signal is then digitized and the digitized waveform is processed further under the control of a microprocessor CPU, e.g., for heartbeat detection, heart rate calculation, arrhythmia detection and classification of the condition of the heart. In prior art monitors the CPU is capable of controlling the ECG lead switch to insure the right combination of lead signals in response to knowledge of the electrode lead configuration presently in place.
However, it is sometimes the case that one or more of the electrodes will become detached as a result of patient movement or were never properly attached in the first place. This will usually result in a distorted or a useless ECG signal with subsequent reduced or nonexistent ability to perform proper ECG analysis. It is highly desirable therefore to be able to automatically detect one or more lead failures and further to automatically switch when possible to an alternate lead configuration which reduces the effect of the lead failure and provides an acceptable ECG signal for processing until the problem can be corrected.